              $\beta$ constant & -7.061 & -6.679 & -6.079 & -3.861 \\
             $\beta$ HP/weight & 2.883 & 2.774 & 2.798 & 5.133 \\
                   $\beta$ air & 1.521 & 0.572 & -0.454 & 1.683 \\
         $\beta$ miles per USD & -0.122 & 0.340 & 0.172 & 0.078 \\
                  $\beta$ size & 3.460 & 3.920 & 3.114 & 4.289 \\
              $\beta$ domestic &   NA &   NA & 0.164 & -0.589 \\
             $\sigma$ constant & 3.612 & 2.962 & 1.731 & 2.441 \\
            $\sigma$ HP/weight & 4.628 & 1.388 & 0.311 & 2.030 \\
                  $\sigma$ air & 1.818 & 1.424 & 2.696 & 0.079 \\
        $\sigma$ miles per USD & 1.050 & 0.072 & 0.015 & 0.258 \\
                 $\sigma$ size & 2.056 & 0.231 & 0.180 & 3.413 \\
             $\sigma$ domestic &   NA &   NA & 0.028 & 0.336 \\
      term on price ($\alpha$) & -43.501 & -45.898 & -39.374 & -76.581 \\
             $\gamma$ constant & 0.952 & 2.785 & 2.406 & 2.127 \\
       $\gamma$ log(HP/weight) & 0.477 & 0.731 & 0.583 & 0.231 \\
                  $\gamma$ air & 0.619 & 0.528 & 0.549 & 0.431 \\
$\gamma$ log(miles per gallon) & -0.415 & -0.651 & -0.479 & -0.323 \\
            $\gamma$ log(size) & -0.046 & -0.472 & 0.249 & 0.776 \\
             $\gamma$ domestic &   NA &   NA & -0.304 & -0.348 \\
                $\gamma$ trend & 0.019 & 0.018 & 0.021 & 0.021 \\
